DNA damage-induced translocation of mitochondrial factor HIGD1A into the nucleus regulates homologous recombination and radio/chemo-sensitivity.

HIGD1A is an important mitochondrial protein recently shown to have a novel nuclear localization under severe stress. However, whether this protein is also associated with the DNA damage response has rarely been studied. Here, we reported that DSBs-induced the translocation of mitochondrial HIGD1A to the nucleus is dependent on nuclear pore complex (NPCs), which finally promotes HR and radio/chemo-resistance. Importantly, NUP93 and HIGD1A physically interact and the interaction domain with NUP93 is located at residues 46-60 of HIGD1A. Chromatin-enriched HIGD1A can then directly interact with RPA. During the early stages of HR, HIGD1A promotes the loading of RPA to DSBs and activates the DNA damage-dependent chromatin association of RAD9-RAD1-HUS1 complex (9-1-1), which stimulates the ATR-Chk1-dependent G2/M DNA damage checkpoint. After facilitating RPA-ssDNA binding, HIGD1A in turn inhibits abnormal persistence of RPA1 foci by promoting ubiquitination of RPA1 and inducing its eventual proteasomal degradation. In addition, we have identified clinical drug Preveon associated with the HIGD1A-NUP93 interaction domain using a virtual screening approach. This compound directly interacted with HIGD1A, which was verified by NMR, and then inhibited HIGD1A translocation. Collectively, we demonstrate a novel role for HIGD1A in DSBs and provide rationale for using HIGD1A inhibitors as cancer therapeutics.